Solvent extraction of vitamin a from fish liver oil



Nov. 6, 1951 S. E. FREEMAN E-rAL SOLVENT EXTRACTION OF VITAMIN A FROM FISH LIVER OIL.

Filed Jan. 29, 1947 i Patented Nov. 6, 1951 SOLVENT EXTRACTION F VITAMINA FROM FISH LIVER 011'. Stephen E. Freeman, Pittsburgh, Pa., and Stewart W. Gloyer, Milwaukee, Wis., burgh Plate Glass Company,

assignors to Pitts- Allegheny County,

Pa., a corporation of Pennsylvania Application January 29, 1947, Serial No. 725,108

9 claims. l

"The present invention relates to separation of concentrates of oil soluble vitamins such as vitamins A and D (if D is present) from certain vitamin bearing oils and has particular relationto the separation of such concentrates by means of organic polar solvents.

One object of the invention is to provide a simple arid inexpensive process of obtaining concentrates of vitamin A suitable for use in capsules and pills from vitamin A containing oils which normally are of too low concentration satisfactorily to be so employed.

A second object is to provide a process of obtaining vitamin A concentrates which is simple and relatively inexpensive to operate.

A third object is so to treat a glyceride oil containing vitamins soluble therein as to eect separation of the oil into a plurality of fractions one of which is greatly enriched in vitamins.

A fourth object is to provide a process of the foregoing type, the application of which does not result in substantial loss of the vitamins in the oil.

A fifth object is to provide a process of obtaining concentrates of vitamins from glyceride oils containing vitamins in low or moderate concentration with selective polar solvents which can with most solvents be operated at temperatures near or not much below normal room temperature.

A sixth object is to provide the process of cbtaining concentrates of oil soluble vitamins by solvent extraction which involves dissolvingQin the solvent a minimum amount of the fatty glycerides of the oil and a maximum amount of the vitamins contained in the oil.

These and other objects of the invention will be apparent from consideration of the following specification and the appended claims.

It has heretofore been proposed to obtain concentrates of oil soluble vitamins such as vitamins A and D from vitamin bearing glyceride oils such as sh liver oils'by various methods. Complicated and expensive chemical procedures have been proposed for the purpose. For example, it has been proposed to saponify the glycerides in the oil with an alkali and then to extract the vitamins from the soaps by means of hydrocarbons. The technique involved was complicated and expensive. It has also been proposed molecularly to distill concentrates of vitamin A from the oils.` The methods of distillation employed for the purpose are highly technical and require the application of very high vacua. The technique is expensive, especially where large volumes of the more plentiful fish liver oils of low or moderate concentration constitute the original source of vitamins and is likely to result in some degree to degradation of the vitamins. In certain patents such as U. S. Patents 2,380,418, 2,380,414, 2,380,4l0,`and 2,347,460 it has been proposed to obtain concentrates of vitamins from vitamin bearing oils by first heating a mixture of oil and a solvent such as isopropyl alcohol in order to dissolve the oil in the solvent and then cooling the solution to a temperature of 0 to 70 C. in order to effect separation of a large portion of the glycerides from the solvent. The vitamins were thus substantially concentrated in the solvent. These patents disclose processes which apparently require batchwise operation. This is true because in some instances the oil is completely dissolved in the solvent. Obviously countercurrent iiow of the components in solution is impossible. In other instances, the oil containing vitamins and the solvent are admixed under conditions of reiiux for the solvent. Countercurrent flow of a reiiuxlng solvent and oil would be highly impractical if not impossible. Such system would also necessitate use of solvents having very low solvency for the oil. Obviously, the techniques involved were slow and expensive.

In certain patents such as U. S. 2,200,390 and 2,200,391 procedures are disclosed for the fractionation of certain glyceride oils to obtain concentrates of the more unsaturated components by liquid phase extraction with organic polar solvents. The procedures as outlined in the patents are not applied to the concentration of vitamins.

In U. S. Patent 2,090,739 to Tischer, it is proposed to wash a vitamin bearing oil such as cod liver oil or the like with a polar solvent such as furfural in order to remove odor, color. and taste constituents from the oil without substantially reducing the vitamin concentration of the oil remaining as a raffinate.

The present invention contemplates a process whereby oils containing vitamins such as vitamins A and D are obtained in high concentration from vitamin bearing oilsl even of low or moderate vitamin concentration by a simple process of liquid phase countercurrent extraction with' organic polar solvents such as are disclosed in the above mentioned Patent y2.200.391 to obtain a major portion of the vitamins in a minor extract portion of the total oil treated. r1

For a better understanding'of the invention reference may now be had to the accompanying drawing in which the single figure diagrammatically illustrates a suitable embodiment of apparatus for obtaining concentrates of vitamins by continuous liquid phase countercurrent extraction of oils such as fish liver oils. In the drawings, like numerals refer to like parts throughout.

In the practice of the invention any one of a number of selective polar solvents may be employed to obtain a fraction of glyceride oils which on a y be seg shaking up a conmplated polar solvent with a sm 3 '4 are greatly enriched in vitamin A simultaneously, ished in vitamins and will contain in soluti vitamin D, if present, will be similarly concenminor amount of the solvent employed.

the solvents will be organic Appropriate polar solvents can usuall disclosed in Patent lected by a simple test involvin ,391 to Stephen E. Freeman. In the patented 5- te all amount separate of the oil to be extracted in a test tube or a eed oil, soy separatory funnel or other suitable laboratory bearing oils, apparatus and observing il.' the oil and the solunsaturation of vent at a denite constant temperature tend to In the patented process 1'0 separate into two liquid phases so that the exnt process, it is required tract or solvent phase will contain 2 to 25% of the in addition to being polar, be original oil. Concentration of vitamins in the extracted oil can easily be determined by Well known chemical, physical or biological tests.

15 The following table illustrates the application be evaporated. The ultiof such test to a. large number of polar solvents. phase will comprise most These 'sts were conducted upon dogsh liver oil nor proportion of the oil in containing about 10,000 units of vitamin A per gram. The same test obviously could be conduct- 20 ed upon other vitamin bearing oil lsuch as cod liver oil, souptln shark liver oil. halibut liver oil and others:

trated. In general polar solvents such as those process the solvents are employed to natural glyceride oils such as lins bean oil, or the like, non-vitamin into fractions upon the basis of the glyceride molecule.

as well as in the prese that the solvents,

but partially miscible with the oil at the temperature of operation so that the oil-solvent system can be separated into two liquid phases from which the solvent can mate or-nal extract of the solvent and a mi which vitamins A and D are highly concentrated. The tlnal raiiinate oil constituting most of the glyceride and especially most of the more saturater glyceride will be correspondingly impover- 00 o 0 o 0 0 o .m aan s sa aan assen. am, aan. a, s 8161213 1.y 714.11m 1.31 8.614,21 B141 4181.111 21883173 94N6543753 H42 365879 9752 55 wn ...D V

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111111 111 11 1111 11 1111 112415 uununnunu una ...Hunan ...Hanna nu Nuno. Memmmm m'mm mo..m.o5.mmw 6655532.136 882 4.44662 9934.64. 55 96 7 1 m I 55. 2 3 mma. ...manna 3.a@ n mana im @cui .manana oaasumasam www annum@ ...anni .2a mu 1 remE e PY if. e IWI m D m mz l m mummm m 1 2 m.. m m D Imo 2 2 m o .nul e n u u n "hh n dAW u u .l h aa 1 mmmm m. t. n Nimah m .mm an I m 1 .mm 0 mm e o .w mwfm. y M fn t :sans m njas: s .w memr. he mm. i u Q .mnlymwm .m md em am v. %1 U mi. M0 o am u m. mol o. ame. m d.. ma m naamw e mmm .wm wa B MA mam.. .a. ma sau n om oss om 2m M Lyv. .m no we nu hz c: mm.1s umn uy o t e Bumm h:mm0 mmammsmmawmc mm am ma te# m Bam wa w msm m am a mamme@ 1.1i et ruh B Ot .l ,BBM 0 t. d 1T .im abni v.. enum .myymnswmmabnw 1 D DomlAm Mmmm l .DAO ewyAm e mwfL:.h...w..wnn nmmmmwaiiamnwwwwmmnwniamty .wmniymw wmmmnmmwm mm nm asuman.. wacpmwsmmwmma @man www time Dmmmsasmw m iammam t .l l .l 11 mMmNmmPmEEMmMDmMc CM myapmdmccEE n .ammFFomDlmmmN NmmmTTmis 1.11 ti. .l m. m. m. m. HH cmu MAA 0 VCEN ANmP B The following constitutes a partial list of some of the more favored polar solvents that can be employed in the operation of the processes herei described:

Methyl lactate Methyl carbitol Methyl acetoacetate Acetonitrile Methyl alcohol Y Monomethyl ether of ethylene glycol Furfuryl alcohol Acetic ,acid f Glycol diacetate Acetonyl acetone Nitromethane Dimethyl formamide Furfural It will be apparent that in each instance where the oils and the polar solvent to be tested were but partially miscible, there was some degree of concentration of the vitamins as determined by appropriate tests for vitamins in the extraction phase, that is the .solvent predominant phase. In some instances the concentration was very pronounced indicating that these solvents would be especially suitable for use as solvents in a counter-current extraction in accordance with commercially feasible methods hereinafter outlined. Counterecurrent extraction is. of course. susceptible of giving much higher degrees of vitamin concentration than the batch extractions'.

Suitable apparatus for commercial operations as diagrammatically illustrated in the drawings includes a column I which constitutes a verti.

cally elongated extraction zone and which may be appropriately packed with rings, saddles, bafiles or the like. The column preferably is fairly long, e. g. 50 ft. or more in the 'extraction zone and it may be provided with suitable means for maintaining a temperature gradient between the top and bottom. Such device may comprise a number of jackets, e. g. upper jacket Illa and lower jacket lllb having inlets I0c and outlets IUd through which a suitable heating transfer medium may be circulated. Other heating or cooling device such as coils in the column for circulating a transfer medium, electrical resistance heaters, or the like may also be employed. The mixture from various positions inthe column may also be withdrawn, passed through a heat exchanger Il'lf to either coolor heat the mixture and finally be repumped back into the column at any desired position. Oil constituting a source of vitamin A or A and D, is brought in as indicated at II from a storage container Ila toa zone approximately at the middle of the column. An appropriate organic polar solvent such as furfural is introduced from container I2 through line |2a into column I0 a short distance below the top of the column in such manner as to provide. a zone I3 in which the separation of the liquid raflinate from the solvent can take place.

The raffinate consisting mainly of a fraction of the original oil impoverished in vitamin A is drawn oil through a. line I4 at the top of the column. It may be delivered to an appropriate still I5 where it is stripped of dissolved solvent.- The vapors of solvent arethen recovered in a condenser I6 and the liquid solvent is recycled to storage I2 through a line IBa. Certain alternative modes of treating the oil will subsequently be described.

The extract oil contained in the solvent will contain in solution most of the vitamins A and D (if D is\present) and is taken off near the bottom of the column through line I1. It likewise may be stripped of solvent in a still such as I8 and the solvent vapors may be passed through conduit I9 to condenser 2| for recovery. The liquid solvent is. drawn of! through lines 22 and IBa to storage tank I2 where it is combined with that from condenser I6.

. scribed. It may constitute the nal extract product of the system in which case it will constitute about 2 to 25% oi' the original oil in which most or a large proportion of the vitamin A preferably is concentrated. Some of this extract oil, e. g. 10 to 95%, stripped, or at least partially stripped of solvent may be recycled or refluxed through a conduit 24 to a zone in column I0, a short distance above the bottom thereof. Usually the extract phase so recycled will contain no more than solvent. The -proportion may be much lower. Assuming that the selective solvent is furfural which is of a density of 1.1598, while sh liver oil isabout .925, evaporation of solvent reduces the density of the resultant solution so that the reux will tend to rise through the` downwardly flowing extract solution. The reux may even be completely stripped. This reiiux increases the vitamin content in the lower zones of the column and thus produces an enriched extract product. The refluxing action may be termed rectification In order to control the ratio of reiiux to extract product taken, suitable control devices are provided. The simplest form of such device of course would involve valves such as valves 21 and 2B in lines 20 and 24. If valve 28 is closed there will be no reflux and the extract oil will pass to storage in a container 29; or if certain alternative procedures are followed, as hereinafter will be described, it may be passed on through line 20a controlled by valve 20h to a. column 3l, which constitutes a second vertically elongated extraction zone, for further extraction.

The column 3| can in the alternative be:

(a) Eliminated from the system, in which instance it is possible to obtain adequate yields of extract containing a concentrate of vitamin A by use of(1) reflux through line 24 and, or (2) by maintaining the upper part of the column at a higher temperature than the lower part, such effect being attained by circulating heat transfer media in jackets Illa and Ib or by feeding in solvent at the top of the column at a higher temperature than the feed oil or by other methods, such as by circulating column solutions through external heat exchangers, such as the heat exchanger I0f where the liquids are cooled or heated as may be required.

(b) A small extract (2 to 25%) of high vitamin concentration can be taken and the raflinate can be re-extracted in column 3l. The second extract can be recovered as a third product or it may be returned to the original feed. The second raflinate is a nal product of use in stock feed or other purposes.

(c) A moderate or large (e. g. 25 to 75%) extract can be taken from column Il) and a correspondingly reduced rafllnate taken preferably as a final relatively low vitamin potency product.

'Ihe extract of a higher vitamin content than the original oil can be re-extracted in column 3| and the second extract taken as the highest vitamin concentrate of the system while the second rafflnate is recovered as a third product or may be recycled to the feed of column I0.

Assuming that one of the alternative methods b or c is employed, solvent from tank I2 is introduced into the column 3| by lines 3Ia at a point slightly below the top of the latter. The raffinate of the column is taken off at the top through line 32 and passes into still 33 where solvent medium may be stripped oiI and and f passed onto condenser 34 for recycling through line 34a to solvent storage. Dependent upon the mode of operation of the system, solvent free raillnate may pass through line 35 to storage in container 36 or, alternatively, it may be returned through a line 35a having a control valve 33h to the oil supply container II a. It will be apparent that since the rainate is usually low in dissolved solvent, it may not be necessary to strip it before recycling it as feed oil to column I0. 'I'he invention, therefore, contemplates recycling of rafflnate from column 3| with or without stripping in still 33, to column I directly through line II in conjunction with original feed oil.

Extract from column 3| which may be a final vitamin concentrate or a product suitable for recycling and mixture with the original feed oil to column I0 dependent upon whether alternative b or c is employed, passes on.' through line 31 to still 38 where the solvent is stripped and delivered through line 39 to condenser 40 and is finally returned-to storage throughlines 4I and 34a. The extract oil is drawn off through line 42. It may go in its entirety to storage 43 or a part may pass through a line 44 to provide reflux to lower vzones of column 3|. This reflux in part controls the vitamin content of the extract of column 3 I. The ratio of reflux may be controlled by valves 45 and 46 which can be opened or closed to determine the ratio of redux of the extract.

Instead of passing the extract oil of column 3| to storage or to reflux in the column, all or a part of it can be sent through line 41 to the feed storage container IIa for return to column I0. Redux through line 44 is again permissible. Valves 48 and 49 in lines 42 and 41 then determine the course of the extract oil from the column 3|.

In the specific examples appended hereto are illustrated conditions oi' operation of the columns I0 and 3| for use with dogflsh oil containing about 10,000 to 20,000 units of vitamin A per gram and with furfural as a polar solvent. Example 1 illustrates the operation of the system in accordance with alternative b in which a small extract fraction of high vitamin content is taken from column III, this constituting the flnal vitamin concentration as obtained from the system. The extract from column 3| is in this instance employed as a part of the feed oil and the raffinate from column 3| is employed as the final low vitamln product of the system.

EXAMPLE 1 Oil used.-Dogsh liver oil containing 10,000 units of vitamin A per gram.

Conditions of operating column Solvent ratio, 8:1 based on oil feed rate Solvent used, anhydrous furfural Oil reflux, none Temperature. 58-80 F. l

Per Cent Taken Imm Units-Vit.

mum Yala um x/zm.

Extract 17.4 no 24,860 aannam su zal 5,840

Conditions of operating column 31 Oil used, raffinate oil from column I0, line 23a Solvent used, anhydrous furfural Solvent ratio, 10:1 based on raffinate oil feed rate,

line 23h Oil redux, none Temperature, 96100 F.

It is to be observed that in this example the second column (3 I) is operated at a substantially higher temperature than the first (Il), thus to obtain the desired vitamin concentrate from the first column. The reflux o! Example 3 or the temperature gradient of Example 4 could be applied in this example.

Per Cent Taken from Units Vit. PMM Yield Line A/gm.

Extract 40.3 42 l2, 300 Ralnate 59. 7 35 2, 100

In the above series of extractions three final products are produced, the yields and potencies of these being given in the following table:

Per Cent Teken from Units Vit. Produc Yield Line Algm.

Extract 17. 4 20 24, 800 2nd Extract. 33. 2 42 l2, 360 2nd Rafliiate- 49. 4 35 2, im Original Oil 10| 000 EXAlWPLEZ Oil used-Dogfish liver oil containing 10,000 units of vitamin A per gram.

Conditions of operating column 10 Solvent ratio, 10:1 based on oil feed rate Solvent used, anhydrous furfural Oil reflux, none Temperature, 93 F.

Per Cent Taken from Units Vit. Pmdlc' Yield Line .1l/gm.

Emacs 50.1 2o 22, ooo Ramnate 49.3 2m 2,260

Conditions of operating column 31 Oil used-Extract oil from column III, lines 2l and 20a.

Solvent used, anhydrous furfural Solvent ratio, 8:1 based on extract oil feed rate,

line 23h Oil reflux, none 16 Temperature, 67 F.

9 It is to be observedithat in this example the second column (3l) is operated at a lower temperature than the rst (I), thus to obtain the lower ratio of extract as the high vitamin con- In the extractions in this example three products are produced, the yields and potencies of these being given in the following table:

Per Cent Units Vit. Products Yield Line A/gm 1st Railinatew 49.3 29a 2, 260 2nd Rauste.. 36. 4 35 7, 460 2nd Extract 14. 3 42 34, 000

The second railnate may be blended with the original feed oil.

In the third example column 3l was cut out of the system and column I0 was operated with a reflux to obtain in the single column a high vitamin extract and a low vitamin rafllnate. The conditions in the system were aslfollows:

Solvent used, anhydrous furfural Solvent ratio, :1 based on oil feed rate Oil reflux, 0.5:1 based on oil feed rate Temperature, 'I0-71 F.

Products Pignt Line Ufgsxt' Extract 28. 8 20 33, 000 Railate 7l. 2 29a 1, 700

In a further example illustrating the practice of the invention relatively high concentrations of vitamins in the extract oil obtained from column I0 was accomplished by maintainance of a temperature gradient between the top and bottom of the column. In this process the temperature gradient may be attained by use of heating or cooling elements at ,appropriate points in the column, for example by means of jackets Illa and I0b lar by use of the heat exchanger lof, which may l be supplied with an appropriate heated liqui or by the employment of solvent at a temperature above that of the feed oil. In the example the second column was not employed. It

obvious that a temperature gradient may also be maintained where a second column is employed to re-extract either the raffinate or the extract from column Ill. The conditions employed where a temperature gradient was maintained and furfural was employed as the polar solvent are illustrated by the following examples:

EXAMPLE 4 Oil used.-Dogsh liver oil containing 17,400 units of vitamin A per gram. f

weight.

Conditions of operating column 10 Solvent used, naphtha saturated furfural Solvent ratio, 8.3 1 based on oil feed rate Oil reux, none Naphtha reflux, 013:1 based on oil feed rate Column temperatures:

Top, 148 F.

Bottom, 48 F.

Units Vita Products Extract 7l, 500 Raftinate 8, 060

The ranate in this example could be used as feed oil in Examples l, 2 or 3 or could be admixed with fresh oil therein and re-extracted to recover a second extract of improved vitamin A concentration. Such second extraction may or may not be preceded by stripping of the solvent in the railinate. In Example 4 it will be apparent that the temperature of the system at the top of the column could have been somewhat higher than given in the example though, of course, it should not be so high as to induce excessive solution of the particular oil being treated. Similarly, the temperature at the bottom of the column may be reduced below the value given in the example but again it should not be so low as to excessively reduce the fraction being taken off. Preferably, the extract will constitute 2 to 25% of the feed oil.

The extract solutions of oil as obtained in the foregoing examples may be further extracted with a parainic hydrocarbon, e. g. a naphtha approximating a heptane to decane in average molecular By such treatment the glycerides and 4 yitamins are washed from the polar solvent, leav- /ing most of the free fatty acids, coloring matter,

odor, and taste constituents concentrated in latter solvent. In such process, the naphtha may be in variable proportion, but 14 to 1 based on oil feed rate is satisfactory. The extraction may be eifected counter-currently in a column at a temperature of about 70 to 75 F. These values are quite appropriate for dogfish liver oil. Some degree of variation for other oils to compensate for differences in solubility of other vitaminiferous oils may be desirable.

In the specific Examples 1 to 4 inclusive the oil treated was dogsh liver oil ,containing vitamin A in the proportions ind/id'ted'. It will be obvious that various others!" aminiferous oils notably of the fish liver type/'such as tuna fish oil, halibut liver, shark liverA oil or other oil may be substituted. With sich substitutions some variation in the temperature values given may be desirable since each of these oils has its own solubility characteristics.

Similarly, it will be apparent that various other polar solvents such as those included in Table A may be substituted for the furfural of Examples 1 to 4 inclusive, the solvents being employed to extract dogsh liver oil or any of the other oils herein enumerated, the temperatures of solubility of the oils found in any of the selective solvents being ,determined by the methods herein discussed. The ratio of solvent to oil may be approximately those values given for purpose of illustration in Table A and the temperatures may also be the same or similar to those tabulated. Though, as in the case of furfural, wide variation of ratios of solvent, for example in the range The vitamin depleted rafllnate oil from the exi traction can be used as a source of vitamin A, e. g. in chicken or cattle feed.

The products as obtained by the foregoing procedures will be of relatively high vitamin A concentration as compared with the oils from which they were derived. 'I'his concentration will vary somewhat dependent upon the vitamin A con- ,centration of the original oil.

These products in most instances are suili- .ciently high in concentration for their use as v'vitamin A concentrates such as are employed ,in 'filling capsules. However, if desired it isv permissible further to treat the oil in order to obtain still higher concentrations of vitamins. For example. the extracted oil containing a very high concentration of vitamins may be suitably saponifled with alkalis such as sodium hydroxide, potassium hydroxide or the like and made up into aqueous alcoholic solutions from which further concentrations of vitamins can be extracted by means of appropriate selective solvents such as .petroleum hydrocarbons. It is also permissible to distill olf concentrations of vitamins from the extracted oil. by so-called molecular distillation in which the extracted oil is subjected to distillation under very low vacuum and in proximity to a cold surface in such manner that the vitamins distilled without actual boiling of the oil. 'Ihese methods of concentration are outlinedin the textbook. Chemistry and Physiology of the Vitamins by H. R. Rosenberg.

An advantage of prelimin'arily extracting the vitamin A bearing oils with polar solvents in accordance with the provisions of the present invention before subjecting them to chemical treatment or to molecular distillation resides in the fact that it is possible greatly thus to reduce the proportion of oil requiring such drastic treatment .as involved in the chemical separation of vitamins or the molecular distillation. The overall expenses of the operation are thus reduced to a substantial degree. Moreover, there is less decomposition of vitamins by reason of the drastic treatment. The raffinate fractions are excellently adapted for food purposes such as stock feeds, or even for human consumption where a a source of vitamins of low concentration is desired.

It will be apparent to those skilled in the art 1 that the forms of the invention herein illustrated are merely by way of examples and that numerous modifications may be made therein without departure from the spirit of the invention or thescope of the appended claims. We claim:

1. A process of obtaining a concentrate of I vitamin A from fish liver oil containing said vitamin which process comprises passing the oil upwardly in countercurrent flow through a vertically elongated zone of downwardly iiowing organic polar solvent whichis partiallyV miscible therewith, the oil-solvent mixture in the upper portion of the zone being maintained at a substantially higher temperature thanthe solvent containing dissolved oil in the lower portion of the zone whereby to obtain a cool extract of glyceride oil and solvent which is highly enriched in vitamin A and a warm raffinate which is correspondingly impoverished in vitamin A, drawing off the raillnate at the top of the zone and the solution of solvent and extract at the bottom of the zone and evaporating the solvent to obtain the concentrate.

2. A process as defined in claim 1 in which the solvent is furfural.

3. In a process of separating a concentrate of vitamin A from a sh liv'er oil containing said vitamin, the steps of continuously flowing one volume of said oil upwardly and flowing three to thirty volumes of organic polar solvent, which is but partially miscible with the oil, downwardly through a vertically elongated zone, the temperature in the zone being within a range of l0 to 80"` C. and being sumcient to effect solution of 25 to '15%` of the feed oil as an extract in the solvent, collecting a liquid rafllnate phase ofoil impoverished in vitamin A at a point above that of introduction of solvent, continuously withdrawing the railinate, collecting the liquid extract of oil in solvent, continuously drawing if oil as an extract phase at a point below that of introduction of the oil, evaporating solvent from the extract phase, passing the oil from said phase upwardly in countercurrent flow through a second vertically elongated zone of downwardly flowing partially miscible solvent, the zone being maintained at a temperature to obtain a second extract solution of oil in solvent and a second 'railinate of oil containing some solvent, collecting the second extract solution at the bottom of the zone, drawing 0H said solution, evaporating off the solvent to obtain the desired concentrate of vitamin A and recycling the second raffinate phase by admixing it with the feed oil to the ilrst extraction zone.

4. A process as defined in claim 3 in which the solvent is furfural.

5. A' process as defined in claim 3 in which the solvent is furfural, the second zone being operated at a substantially lower temperature than the rst.

6. In'a process of obtaining a concentrate of vitamin A from a fish liver oil containing said vitamin, the steps comprising owing one volume of the oil upwardly in intimate contact with three to thirty volumes of downwardly flowing organic polar solvent which is but partially miscible with the oil at temperatures of 10 to 80 C., the zone being at a temperature adapted to obtain a liquid extract solution of 25 to 75% of the oil in the solvent, drawing off the liquid extract solution of oil and solvent at the bottom 0f the zone, evaporating the solvent from the extract solution, then further intimately countercurrently contacting the extracted oil with polar solvent in a second elongated zone to obtain an overall extraction of about 15% of the oil, then evaporating the solvent from the resultant liquid extract phase to obtain an extract product which is greatly enriched in vitamin A as compared with the original oil.

7. A process of obtaining a concentrate of vitamin A from fish liver oil which process comprises flowing one volume of the oil upwardly through three to thirty volumes of downwardly flowing organic polar solvent which is but partially miscible with the oil at temperatures of 10 to 80 C., in a vertically elongated zone at a temperature to obtain an extract yield of 2 to 25% 7g of the original oil, continuously drawing on a liquid raffinate of oil impoverished in vitamin A at the top of the zone and an extract solution of solvent and 2 to 25% of the original oil at the bottom of the zone, the' concentration of vitamin A in the oil of the extract solution being et least twice as great as the original oil, evaporating the solvent from the extract solution and returning to 90% thereof to said zone at a point below that of introduction of the feed oil and above the point of withdrawal of the extract solution.

8. A process as defined in claim 7 in which the solvent is furfural.

9. A continuous process for preparing a vitamin A concentrate from a charge oil which is a sh liver oil containing vitamin A, by fractionation with furfural at a temperature within a range of 10 to 80.I C., said process being carried out in a vertically extended fractionation zone having a furfural, inlet and a raffinate phase outlet near the upper end, an extract phase outlet near the lower end and a charge oil inlet in the intermediate portion of said zone, which process includes the steps of continuously introducing said charge oil and said furfural into a vertically extended fractionation zone having a furfural inlet and a raffinate phase outlet near the upper end, an extract phase outlet near the lower end and a charge oil inlet in the intermediate portion of said zone; separately withdrawing extract and raffinate phases from said extract phase outlet and said ranate phase outlet respectively, said extract phase constituting about 2 to 25% of the original feed oil and having a temperature in the range of 10 to 80 C., separating furfural from at least a part of said extract phase to produce a reflux liquid having substantially lower density than said extract phase, and owing said 14 reflux liquid upwardly in said fractionation zone to contact and rectify said downwardly flowing extract phase; maintaining the rate of flow of said reflux liquid to produce at some point within the fractionation zone a reflux flow rate in the range of 10 to 90% of therate at which extractoil is withdrawn from said fractionation zone; maintaining furfural introduction at said furfural inlet at a rate in a range of 3 to 30 volumes of furfural to one volume of charge oil;

` and recovering a vitamin concentrate product.

from said extract phase.

STEPHEN E. FREEM'AN. STEWART W. GLOYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Rosenberg, Chemistry and Phys. of the mins (1942) ,page 60.

Chemical and Engineering News (1941), vol.

Vita- I 19, page 624. 

1. A PROCESS OF OBTAINING A CONCENTRATE OF VITAMIN A FROM FISH LIVER OIL CONTAINING SAID VITAMIN WHICH PROCESS COMPRISING PASSING THE OIL UPWARDLY IN COUNTERCURRENT FLOW THROUGH A VERTICALLY ELONGATED ZONE OF DOWNWARDLY FLOWING ORGANIC POLAR SOLVENT WHICH IS PARTIALLY MISCIBLE THEREWITH, THE OIL-SOLVENT MIXTURE IN THE UPPER PORTION OF THE ZONE BEING MAINTAINED AT A SUBSTANTIALLY HIGHER TEMPERATURE THAN THE SOLVENT CONTAINING DISSOLVED OIL IN THE LOWER PORTION OF THE ZONE WHEREBY TO OBTAIN A COOL EXTRACT OF GLYCERIDE OIL AND SOLVENT WHICH IS HIGHLY ENRICHED IN VITAMIN A AND A WARM RAFFINATE WHICH IS CORRESPONDINGLY IMPOVERISHED IN VITAMIN A, DRAWING OFF THE RAFFINATE AT THE TOP OF THE ZONE AND THE SOLUTION OF SOLVENT AND EXTRACT AT THE BOTTOM OF THE ZONE AND EVAPORATING THE SOLVENT TO OBTAIN THE CONCENTRATE. 